Capacitor element, manufacturing method therefor, semiconductor device substrate, and semiconductor device

ABSTRACT

A capacitor element configured to mount a semiconductor element thereon includes a base. A capacitor part is provided on the base. The base is made of a resin whose coefficient of linear expansion is adjusted in accordance with a coefficient of linear expansion of the semiconductor element mounted on the capacitor element.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to capacitor elements, manufacturingmethods therefor, and substrates for semiconductor devices havingcapacitor elements.

2. Description of the Related Art

Recently, in semiconductor devices, operating frequencies ofsemiconductor elements thereof are becoming higher. Based on this, it isbecoming necessary to stabilize power supply voltages supplied to thesemiconductor elements. In order to deal with this necessity, astructure has been proposed in which a capacitor element is provided ina substrate (semiconductor device substrate) for a semiconductor deviceon which substrate a semiconductor element is mounted.

FIG. 1 shows a conventional semiconductor device 10. The semiconductordevice 10 has a structure in which a semiconductor element 12 is mountedon a semiconductor device substrate 11. The substrate 11 has a structurein which a capacitor element 14 is provided inside a substrate body 13.The capacitor element 14 has a structure in which a film 16 made of adielectric material is formed on a top surface of a silicon substrate15, and a conductive film 17 is formed on the film 16 (refer to JapaneseLaid-Open Patent Application No. 2001-274034, for example).

The capacitor element 14 has the structure in which the siliconsubstrate 15 serves as the base. Hence, when forming a through-hole inthe silicon substrate 15, it is necessary to perform dry etching, wetetching, or laser processing, for example, which results in a furtherprocess in manufacturing. In addition, since the silicon substrate 15 isa semiconductor, it is necessary to form an insulating film on theinside surface of the through-hole and the top surface of the siliconsubstrate 15 before filling the through-hole with Cu, for example, so asto secure insulation. This also results in a further process inmanufacturing.

When the thickness of a silicon substrate is reduced, the strength isdecreased and cracking tends to occur. Hence, it is difficult to reducethe thickness. Here, the base is the silicon substrate 15. Thus, thethickness of the capacitor element 14 cannot be reduced, and thethickness of the substrate 11 is increased for that amount.

The capacitor element 14 is arranged at a position distant from asemiconductor element mounting surface of the substrate 11. Thus, theconductive channel between the semiconductor element 12 and thecapacitor element 14 is long, and the inductance thereof is high. Hence,in a case where the operating frequency of the semiconductor element 12becomes higher, there is the possibility that stabilization of powersupply voltage supplied to the semiconductor element 12 becomesdifficult due to the inductance.

SUMMARY OF THE INVENTION

A general object of the present invention is to provide an improved anduseful capacitor element, a manufacturing method therefor, and asubstrate (semiconductor device substrate) for a semiconductor devicehaving the capacitance element in which one or more of theabove-mentioned problems are eliminated.

Another object of the present invention is to provide a capacitorelement embedded in a semiconductor device substrate, having a reducedthickness, and improving productivity.

In order to achieve the above-mentioned objects, according to one aspectof the present invention, there is provided a capacitor elementconfigured to mount a semiconductor element thereon, the capacitorelement including:

a base; and

a capacitor part provided on the base,

wherein the base is made of a resin whose coefficient of linearexpansion is adjusted in accordance with a coefficient of linearexpansion of the semiconductor element.

Since the base is made of the resin, it becomes easier to reduce thethickness of a capacitor element compared to that of a capacitor havinga silicon substrate as the base. In addition, since the capacitorelement is thin, the thickness of a substrate for mounting an elementembedding the capacitor element therein is also reduced.

Additionally, since the base is made of the resin whose coefficient oflinear expansion is adjusted, in a case where an element is mounted onthe substrate embedding the capacitor element therein, heat stressgenerated between the capacitor element and the mounted element iscontrolled to be small.

In the above-mentioned capacitor element, the base may be made of anepoxy resin including a filler for adjusting the coefficient of linearexpansion of the epoxy resin to fall within the range of 5–30 ppm/K.

In this case, since the base is made of epoxy resin whose coefficient oflinear expansion is within the range of 5–30 ppm/K, the coefficient oflinear expansion of the capacitor element becomes close to that of asemiconductor element having a silicon substrate. Consequently, when thesemiconductor element is mounted on the semiconductor device substrateembedding the capacitor element therein, heat stress generated betweenthe capacitor element and the mounted semiconductor element iscontrolled to be small.

Additionally, the base may be made of a polyimide resin including afiller for adjusting the coefficient of linear expansion of thepolyimide resin to fall within the range of 5–30 ppm/K.

Since the base is made of polyimide resin whose coefficient of linearexpansion is within the range of 5–30 ppm/K, the coefficient of linearexpansion of the capacitor element becomes close to that of asemiconductor element having a silicon substrate. Accordingly, when thesemiconductor element is mounted on the substrate embedding thecapacitor element therein, heat stress generated between the capacitorelement and the mounted semiconductor element is controlled to be small.

Additionally, the base may be made of thermoplastic liquid crystalpolymer whose coefficient of linear expansion is within the range of5–30 ppm/K.

Since the base is made of thermoplastic liquid crystal polymer whosecoefficient of linear expansion is within the range of 5–30 ppm/K, thecoefficient of linear expansion of the capacitor element becomes closeto that of a semiconductor element having a silicon substrate. Thus,when the semiconductor element is mounted on the substrate embedding thecapacitor element therein, heat stress generated between the capacitorelement and the mounted semiconductor element is controlled to be small.

Additionally, the base may be made of a resin including aramid fiber foradjusting the coefficient of linear expansion of the resin to fallwithin the range of 5–30 ppm/K.

Since the base is made of the resin whose coefficient of linearexpansion is within the range of 5–30 ppm/K, the coefficient of linearexpansion of the capacitor element becomes close to that of asemiconductor element having a silicon substrate. Thus, when thesemiconductor element is mounted on the substrate embedding thecapacitor element therein, heat stress generated between the capacitorelement and the mounted semiconductor element is controlled to be small.

Additionally, according to another aspect of the present invention,there is provided a method of manufacturing a capacitor elementincluding the steps of:

applying on a surface of a base material a base made of a resin whosecoefficient of linear expansion is adjusted in accordance with acoefficient of linear expansion of a semiconductor element mounted onthe capacitor element;

forming vias in the base;

forming a conductive layer on a top surface of the base;

patterning the conductive layer so as to form terminals filling in thevias and lower electrodes extending to the top surface of the base;

forming a dielectric layer on the lower electrodes;

forming a conductive layer on a top surface of the dielectric layer; and

patterning the conductive layer so as to form on the dielectric layer anupper electrode opposing the lower electrodes and so as to form aterminal having an exposed top surface.

Since the base made of resin is used, compared to the case where asilicon substrate is used, formation of the vias becomes easier. Thus,it becomes possible to reduce the time interval required for anoperation to form the vias. In addition, since the base is made ofinsulative resin, it becomes possible to directly form a conductivelayer on the top surface of the base without forming an insulating film.Accordingly, compared to the case where a silicon substrate is used,manufacturing processes are reduced.

Additionally, according to another aspect of the present invention,there is provided a semiconductor device substrate on which asemiconductor element may be mounted, the semiconductor device substrateincluding:

a substrate body having a bottom surface that serves as a mountingsurface in which external connection terminals are arranged; and

a capacitor element including:

-   -   a base made of a resin whose coefficient of linear expansion is        adjusted in accordance with the semiconductor element to be        mounted;    -   a capacitor part including two opposing electrodes and a        dielectric layer interposed therebetween;    -   a plurality of terminals in a top surface of the capacitor        element; and    -   a plurality of terminals in a bottom surface of the capacitor        element,

the capacitor element being embedded in the substrate body, a topsurface of the capacitor element being exposed at a top surface of thesubstrate body and serving as a surface on which the semiconductorelement may be mounted.

Since the capacitor element includes the base made of resin and thus thethickness of the capacitor element is reduced, it also becomes possibleto reduce the thickness of a substrate (semiconductor device substrate)for semiconductor device. In addition, the top surface of the capacitorelement serves as a surface (semiconductor element mounting surface) onwhich a semiconductor element is mounted. Thus, the length of aconductive channel between the capacitor part and the semiconductorelement mounting surface is shorted to such an extent that the lengthcannot be made any shorter. Accordingly, it becomes possible to reduceparasitic inductance, which is inductance of the conductive channelbetween the capacitor part and terminals on the semiconductor elementmounting surface, to such an extent that the parasitic inductance cannotbe reduced any further. Hence, even if a semiconductor element ismounted that is operated at a high speed and is subject to parasiticinductance, power supply voltage is stabilized. Thus, the semiconductordevice substrate is suitable for mounting a semiconductor elementoperated at a high speed.

Additionally, according to another aspect of the present invention,there is provided a semiconductor device including:

the semiconductor device substrate as mentioned above; and

a semiconductor element,

the semiconductor element being mounted on a top surface of thesemiconductor device substrate at which the capacitor element isexposed.

Since the semiconductor element is mounted on the top surface of thecapacitor element, the length of a conductive channel between themounted semiconductor element and the capacitor part is shortened tosuch an extent that the length cannot be made any shorter. Accordingly,it becomes possible to reduce parasitic inductance, which is inductanceof the conductive channel between the mounted semiconductor element andthe capacitor part, to such an extent that the parasitic inductancecannot be reduced any further. Hence, even if a semiconductor element ismounted that is operated at a high speed and is subject to the parasiticinductance, power supply voltage is stabilized. In addition, heat stressgenerated between the capacitor element and the semiconductor element iscontrolled to be small.

Other objects, features and advantages of the present invention willbecome more apparent from the following detailed description when readin conjunction with the following drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram showing a conventional example;

FIG. 2 is a schematic diagram showing a capacitor element according toone embodiment of the present invention;

FIG. 3 is a schematic diagram showing a manufacturing flow of thecapacitor element shown in FIG. 2;

FIG. 4 is a schematic diagram showing the subsequent manufacturing flowof that shown in FIG. 3;

FIG. 5 is a schematic diagram showing the subsequent manufacturing flowof that shown in FIG. 4;

FIG. 6 is a schematic diagram showing a semiconductor device substrateaccording to one embodiment of the present invention;

FIG. 7 is a schematic diagram showing an internal structure of thecapacitor element and a connection part of the capacitor element and thesubstrate shown in FIG. 6 in an enlarged manner;

FIG. 8 is a schematic diagram showing a semiconductor device having thesemiconductor device substrate shown in FIG. 6;

FIG. 9 is a schematic diagram showing a connection part of asemiconductor element and the capacitor element in an enlarged manner;

FIG. 10 is a schematic diagram showing a manufacturing flow of thesemiconductor device substrate shown in FIG. 6;

FIG. 11 is a schematic diagram showing the subsequent manufacturing flowof that shown in FIG. 10; and

FIG. 12 is a schematic diagram showing the subsequent manufacturing flowof that shown in FIG. 11.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Descriptions are given below in the order of a capacitor element, amanufacturing method therefor, a substrate (hereinafter referred to as a“semiconductor device substrate”) for a semiconductor device, asemiconductor device, and a manufacturing method of the semiconductordevice substrate.

First, a description is given below of one embodiment of a capacitorelement and a manufacturing method therefor.

FIG. 2-(A) shows a capacitor element 20 according to one embodiment ofthe present invention. The capacitor element 20 is in a sheetfragment-like shape. FIG. 2-(B) and FIG. 2-(C) show cross-sectionalviews taken along the lines B—B and C—C in FIG. 2-(A), respectively.

As shown in FIG. 6, the capacitor element 20 is used by being embeddedin a semiconductor device substrate 100 such that the capacitor element20 is exposed at the surface of the semiconductor device substrate 100.The capacitor element 20 constitutes a part of the semiconductor devicesubstrate 100, and forms a mounting portion for a semiconductor element.As shown in FIG. 8, an LSI semiconductor element 140 is mounted on themounting portion, thereby constituting a semiconductor device 130.

As shown in FIG. 2-(A), the capacitor element 20 includes a base 21serving as a core substrate; a thin film capacitor part (capacitor part)22 formed on the top surface of the base 21; an insulative protectivefilm (protective film) 23 covering the capacitor part 22 and formedabove the base 21; lower terminals (signal lower terminals) 24 and 25for signal, a lower terminal (power source lower terminal) 26 for powersource, and two lower terminals (grounding lower terminals) 27-1 and27-2 for grounding that are exposed at a bottom surface 30 of thecapacitor element 20; and upper terminals (signal upper terminals) 44and 45 for signal, an upper terminal (power source upper terminal) 46for power source, and two upper terminals (grounding upper terminals)47-1 and 47-2 for grounding that are arranged in a top surface 31 of thecapacitor element 20.

The base 21 is a sheet fragment made of epoxy resin including a silicainorganic filler. The base 21 includes the silica inorganic filler foradjusting the coefficient of linear expansion. The coefficient of linearexpansion of the base 21 is adjusted to fall within the range of 5–30ppm/K in consideration of the coefficient of linear expansion(approximately 3 ppm/K) of a silicon substrate, which serves as a coresubstrate of the LSI semiconductor device 140. Since the base 21 is madeof epoxy resin, it is not difficult to reduce a thickness t1 to be lessthan 50 μm. Moreover, even if the thickness t1 is less than 50 μm,mechanical strength is sufficiently high, and further, flexibility isprovided.

The signal upper terminals 44 and 45, the power source upper terminal46, and the two grounding upper terminals 47-1 and 47-2 are arranged soas to correspond to bumps 141 of a semiconductor element to be mounted.The two upper terminals 47-1 and 47-2 are positioned on both sides ofthe upper terminal 46. Each of the signal upper terminals 44 and 45, thepower source upper terminal 46, and the grounding upper terminals 47-1and 47-2 includes a Ni/Au plating part 48. Thus, oxidization of exposedsurfaces of the signal upper terminals 44 and 45, the power source upperterminal 46, and the grounding upper terminals 47-1 and 47-2 that aremade of Cu is prevented. The signal lower terminals 24 and 25, the powersource lower terminal 26, and the two grounding lower terminals 27-1 and27-2 correspond to the signal upper terminals 44 and 45, the powersource upper terminal 46, and the two grounding upper terminals 47-1 and47-2, respectively.

The capacitor part 22 has a structure in which a lower electrode 32 andan upper electrode 33 face each other and have interposed therebetween atantalum anodized oxide layer (dielectric layer, hereinafter referred toas a “anodized oxide layer”) 34. The capacitor part 22 is arranged onthe base 21, and covered and protected by the protective film 23. Theanodized oxide layer 34 is formed on a surface of the lower electrode32. The lower electrode 32 shown in the left portion of FIG. 4-(A) iselectrically connected with the lower terminal 27-1, and the lowerelectrode 32 shown in the right portion of FIG. 4-(A) is electricallyconnected with the lower terminal 27-2. The upper electrode 33 iselectrically connected with the power source lower terminal 26. Thecapacitor part 22 is provided between the power source lower terminal 26and the grounding lower terminals 27-1 and 27-2. When the capacitorelement 20 is embedded in a semiconductor device substrate as describedlater, a semiconductor device including a semiconductor element ismounted on a printed-circuit board, and the semiconductor device isoperated, the capacitor part 22 functions as a bypass capacitor or adecoupling capacitor. Consequently, the power supply voltage supplied tothe semiconductor element is stabilized.

When the capacitor element 20 does not have a semiconductor elementmounted thereon, regarding the capacitor part 22, the source lowerterminal 26 and the power source upper terminal 46 form one terminal,and the grounding lower terminal 27-1 and the grounding upper terminal47-1 form the other terminal.

Since the base 21 is the sheet fragment having the thickness t1 lessthan 50 μm, a thickness t10 of the capacitor element 20 is small. Inaddition, since the base 21 has flexibility, the capacitor element 20also has flexibility.

It should be noted that the coefficient of linear expansion of thecapacitor element 20 corresponds to that of the base 21 and is withinthe range of 5–30 ppm/K. As described later, the coefficient of linearexpansion of the capacitor element 20 has the intermediatecharacteristic between that of a substrate body for a semiconductordevice and that (approximately 3 ppm/K) of a silicon substrate that is amaterial of the semiconductor element, and has a value close to thecoefficient of linear expansion of a silicon substrate. Accordingly, inthe semiconductor device 130, which is shown in FIG. 8 and describedlater, heat stress between the semiconductor element and the capacitorelement 20, and heat stress between the capacitor element 20 and thesubstrate body for the semiconductor device 130 are both decreased andimproved.

It should be noted that the base 21 may be a sheet fragment made ofpolyimide resin including a silica inorganic filler and having acoefficient of linear expansion within the range of 5–30 ppm/K.Additionally, the base 21 may be a thermoplastic liquid crystal polymerwhose coefficient of linear expansion is within the range of 5–30 ppm/K.Further, the base 21 may be made of an epoxy resin including aramidfiber and having a coefficient of linear expansion within the range of5–30 ppm/K.

Next, referring to FIGS. 3, 4 and 5, a description is given below of amanufacturing method of the above-mentioned capacitor element 20.

In practice, the capacitor element 20 is manufactured by arranging andforming a large number of pairs of capacitor parts 22 in a matrix-likemanner on a large size resin sheet, and individualizing them at last.For convenience of explanation, however, a description is given of amethod of manufacturing one capacitor element 20 by processing the base21 having the size corresponding to the capacitor element 20.

First, as shown in FIG. 3-(A), a release agent film 51 is formed on thetop surface of a base material 50, and the base 21 is applied on therelease agent film 51. A film of Cr, Ni, or Sn may be used as asubstitute for the release agent film 51.

Then, as shown in FIG. 3-(B), vias 52 are formed in the base 21 by laserprocessing or dry etching, for example. Since the base 21 is made ofepoxy resin, formation of the vias 52 is completed in a shorter timeinterval compared to the case of forming vias in a silicon substrate.

Then, as shown in FIG. 3-(C), electroless copper plating andelectrolytic copper plating are conducted on surfaces of the base 21 soas to form a copper plating layer 53 such that the copper plating layer53 covers the top surfaces and side surfaces of the base 21 and fills inthe vias 52. In FIG. 3-(C), 54 denotes copper portions that fill in thevias 52, and 55 denotes a copper layer on the top surfaces of the base21. A conductive resin film may be formed on the surfaces of the base 21as a substitute for the copper plating layer 53.

Then, as shown in FIG. 4-(A), the copper layer 55 is subjected topatterning, thereby segmentalizing the copper portions 54 that fill inthe respective vias 52 so as to form the signal lower terminals 24 and25, the power source lower terminal 26, and the two grounding lowerterminals 27-1 and 27-2, and forming the lower electrodes 32 extendingtoward the power source lower terminal 26 from the lower terminals 27-1and 27-2 (refer to FIG. 2(B)).

Then, as shown in FIG. 4-(B), a tantalum film (34 and 56) is formed onsurfaces of the base 21 by sputtering tantalum thereon, and a tantalumoxide film is formed by anodizing the tantalum film.

Then, the tantalum oxide film is subjected to etching and patterningsuch that the tantalum oxide film remains on the lower electrodes 32,and the top surfaces of the signal lower terminals 24 and 25, the powersource lower terminal 26, and the grounding lower terminals 27-1 and27-2 are exposed, thereby forming dielectric layers 56 (refer to FIG.2-(B)). Among the dielectric layers 56, those formed on the lowerelectrodes 32 constitute the dielectric layers 34 of the capacitor part22. Sputtering of tantalum is conducted at a temperature of 200° C. orless. Hence, the dielectric layers 34 are formed without givingdetrimental effect on the base 21 that is made of epoxy resin. It shouldbe noted that Ti, Si, or Al, for example, which are valve metals, may beused as a substitute for tantalum.

Then, as shown in FIG. 4-(C), electroless copper plating is conducted onthe surfaces of the dielectric layers 34 so as to form a copper platinglayer 53. The copper plate layer 53 is subjected to etching andpatterning such that the copper plating layer 53 remains on the topsurfaces of the dielectric layers 34 and the top surfaces of the signallower terminals 24 and 25, the power source lower terminal 26, and thegrounding lower terminals 27-1 and 27-2, thereby forming the upperelectrode 33, the signal upper terminals 44 and 45, the power sourceupper terminal 46, and the two grounding upper terminals 47-1 and 47-2(refer to FIG. 2-(C)). Upon formation of the upper electrode 33, thecapacitor part 22 is constructed.

Then, as shown in FIG. 5-(A), an insulative film is formed on the topsurfaces and the peripheral side surfaces by forming photosensitiveresist. The insulative film is subjected to patterning such that thesignal upper terminals 44 and 45, the power source upper terminal 46,and the grounding upper terminals 47-1 and 47-2 are exposed, therebyforming the protective film 23 (refer to FIG. 2-(C)).

Then, as shown in FIG. 5-(B), the Ni/Au plating parts 48 are formed byperforming surface treatment on the exposed top surfaces of the signalupper terminals 44 and 45, the power source upper terminal 46, and thegrounding upper terminals 47-1 and 47-2 by conducting Ni/Au plating.

Here, the capacitor element 20 is completed on the base 21.

Finally, as shown in FIG. 5-(C), the capacitor element 20 is separatedfrom the base material 50 by reducing adhesion of the release agent film51 by illuminating light or applying heat. When the base material 50 isa glass board, it is preferred to illuminate light. Additionally, inFIG. 3-(A), when a film of Cr, Ni, or Sn is formed as a substitute forthe release agent film 51, the film of Cr, Ni, or Sn is removed by wetetching, thereby separating the capacitor element 20 from the basematerial 50.

Next, a description is given below of a semiconductor device substrate.

FIG. 6 shows the substrate 100 for semiconductor device. FIG. 7 shows apart of the substrate 100 in an enlarged manner.

The substrate 100 includes a substrate body 101 and the capacitorelement 20 embedded in the top surface of the substrate body 101. Thecapacitor element 20 is embedded in a resin layer 104 with the topsurface exposed at the top surface of the substrate 100. The substratebody 101 is a multilayer circuit board in which resin layers 102, 103and 104 are stacked. A conductive pattern formed for each of the layers102, 103 and 104 is electrically connected by vias 106 that run througheach of the layers 102, 103 and 104. Conductive channels (signalconductive channels) 124 and 125 for signal, a conductive channel (powersource conductive channel) 126 for power source, and conductive channels(grounding conductive channels) 127-1 and 127-2 for grounding are formedinside the substrate body 101 such that the above-mentioned channels runthrough the substrate body 101 in the thickness direction thereof.

110 denotes a surface on which a semiconductor element is mounted. Thesurface 110 is the top surface of the capacitor element 20. As shown inFIG. 7, the signal upper terminals 44 and 45, the power source upperterminal 46, and the two grounding upper terminals 47-1 and 47-2 arearranged in the surface 110.

115 (FIG. 6) denotes a mounting surface, which is the bottom surface ofthe substrate body 101. Solder balls 116 are provided in the mountingsurface 115 such that the solder balls 116 are connected to the vias106. The mounting surface 115 is covered with solder resist 117.

The signal lower terminals 24 and 25, the power source lower terminal26, and the grounding lower terminals 27-1 and 27-2 of the capacitorelement 20 are connected to the vias 156. The capacitor part 22 of thecapacitor element 20 is connected between the power source conductivechannel 126 and the grounding conductive channels 127-1 and 127-2.

As shown in FIG. 7, a distance a1 of a conductive channel between thetop surface of the power source upper terminal 46 and the capacitor part22, and a distance b1 of a conductive channel between the top surface ofthe grounding upper terminal 47-1 and the capacitor part 22 are bothvery short. Also, a distance a2 of a conductive channel between the topsurface of the power source upper terminal 46 and another capacitor part22, and a distance b2 of a conductive channel between the top surface ofthe grounding upper terminal 47-2 and the capacitor part 22 are bothvery short. Accordingly, parasitic inductance, which is inductance ofthe conductive channels, is very small.

Additionally, since the capacitor element 20 is thin and embedded in oneresin layer 104, a thickness t20 of the substrate 100 is small. Thethickness of the resin layer 104 is several dozen μm, for example.

FIGS. 8 and 9 show the semiconductor device 130. In the semiconductordevice 130, the semiconductor element 140 is mounted on the surface 110of the substrate 100 shown in FIGS. 6 and 7 by flip chip bonding. Thebumps 141 on the bottom surface of the semiconductor element 140 areconnected to the signal upper terminals 44 and 45, the power sourceupper terminal 46, and the two grounding upper terminals 47-1 and 47-2that are in the surface 110. 142 denotes an under fill.

The capacitor element 20 is arranged at a position beneath thesemiconductor element 140. Hence, a conductive channel between thesemiconductor element 140 and the capacitor element 20 is very short,and parasitic inductance, which is inductance of the conductive channel,is very small. Accordingly, even if the operating frequency of thesemiconductor element 140 becomes higher, power supply voltage suppliedto the semiconductor element 140 is maintained to be stable withoutbeing affected by the parasitic inductance.

In practice, the semiconductor element 140 is mounted on the capacitorelement 20, and the capacitor element 20 has a coefficient of linearexpansion that is substantially the same as that of the semiconductorelement 140 made of silicon. Thus, in a case where the semiconductorelement 140 generates heat at the time of operation, and the capacitorelement 20 is heated by the semiconductor element 140, heat stressgenerated between the semiconductor element 140 and the capacitorelement 20 is controlled to be small and improved.

Next, referring to FIGS. 10, 11, and 12, a description is given below ofa manufacturing method of the substrate 100.

First, as shown in FIG. 10-(A), a thin resin film 151 is formed byapplying resin such as polyimide on the top surface of a metal plate 150made of copper, for example.

Then, as shown in FIG. 10-(B), the capacitor element 20 shown in FIG. 2is mounted on the thin resin film 151 with the position reversed fromthat shown in FIG. 2.

Then, as shown in FIG. 10-(C), the capacitor element 20 is laminated andcovered by a resin layer 104 made of epoxy, for example. The resin layer104 fills in clearances between the capacitor element 20 and the thinresin film 151.

Then, as shown in FIG. 10-(D), concave portions 153 for forming vias areformed in the resin layer 104 by laser processing or etching, forexample. The signal lower terminals 24 and 25, the power source lowerterminal 26, and the grounding lower terminals 27-1 and 27-2 are exposedat the bottom surfaces of the concave portions 153.

Then, as shown in FIG. 11-(A), a metal layer 154 is formed over theresin layer 104 by performing electroless copper plating andelectrolytic copper plating. The metal layer 154 fills in the concaveportions 153.

Then, as shown in FIG. 11-(B), a conductive pattern 155 and vias 156 areformed by patterning the metal layer 154 by a photolithography method.

Then, as shown in FIG. 11-(C), the conductive pattern 155 is laminatedby a resin layer 103 such that the conductive pattern 155 is covered bythe resin layer 103. Concave portions 157 for forming vias are formed inthe resin layer 103 by laser processing or etching, for example. Theconductive pattern 155 and the vias 156 are exposed from the bottomsurfaces of the concave portions 157.

Then, as shown in FIG. 12-(A), a metal layer is formed over the resinlayer 103. A conductive pattern 158 and vias 159 are formed bypatterning the metal layer. Further, a resin layer 102 is formed on theresin layer 103, and concave portions for forming vias are formed in theresin layer 102. A metal layer is formed over the resin layer 102, andvias 160 and pads 161 are formed by patterning the metal layer.

Then, as shown in FIG. 12-(B), solder resist 117 is applied over theresin layer 102 except portions of the pads 161.

Finally, as shown in FIG. 12-(C), etching is performed on the metalplate 150 to remove the metal plate 150.

The process of etching performed on the metal plate 150 is stopped bythe thin resin layer 151. Thus, excessive etching is prevented. Afterremoving the metal plate 150, the thin resin layer 151 is removed by dryetching. The solder balls 116 are bonded to the pads 161 by placing andreflowing the solder balls 116 in the concave portions formed in thesolder resist 117.

It is also possible to use the capacitor element 20, for other use, forexample, by embedding the capacitor element 20 in a substrate other thanthe substrate 100.

As mentioned above, according to the present invention, since the base21 is made of resin, it becomes easier to reduce the thickness of acapacitor element 20 and form vias, compared to the case of a capacitorelement having a silicon substrate as the base. Thus, it becomespossible to more easily manufacture a capacitor element. In addition,since the capacitor element 20 may be made comparatively thinner, thethickness of a substrate (element mounting substrate) for mounting anelement embedding the capacitor element 20 therein may also be reduced.Further, since the base 21 is made of a resin whose coefficient oflinear expansion is adjusted, in the case where an element is mounted onthe element mounting substrate embedding the capacitor element 20therein, it is possible to control heat stress generated between thecapacitor element 20 and the mounted element to be small.

In the above-mentioned capacitor element 20, the base 21 may include afiller and be made of epoxy resin whose coefficient of linear expansionis within the range of 5–30 ppm/K. In this case, since the base 21 ismade of epoxy resin whose coefficient of linear expansion is within therange of 5–30 ppm/K, the coefficient of linear expansion of thecapacitor element 20 becomes close to that of a semiconductor elementhaving a silicon substrate. Consequently, when the semiconductor elementis mounted on the semiconductor device substrate embedding the capacitorelement 20 therein, it is possible to control heat stress generatedbetween the capacitor element 20 and the mounted semiconductor elementto be small.

Additionally, the base 21 may include a filler and be made of polyimideresin whose coefficient of linear expansion is within the range of 5–30ppm/K. In this case, since the base 21 is made of polyimide resin whosecoefficient of linear expansion is within the range of 5–30 ppm/K, thecoefficient of linear expansion of the capacitor element 20 becomesclose to that of a semiconductor element having a silicon substrate.Accordingly, in a case where the semiconductor element is mounted on thesemiconductor device substrate embedding the capacitor element 20therein, it is possible to control heat stress generated between thecapacitor element 20 and the mounted semiconductor element to be small.

Additionally, the base 21 may be made of thermoplastic liquid crystalpolymer whose coefficient of linear expansion is within the range of5–30 ppm/K. In this case, since the base 21 is made of thermoplasticliquid crystal polymer whose coefficient of linear expansion is withinthe range of 5–30 ppm/K, the coefficient of linear expansion of thecapacitor element 20 becomes close to that of a semiconductor elementhaving a silicon substrate. Thus, in a case where the semiconductorelement is mounted on the semiconductor device substrate embedding thecapacitor element 20 therein, it is possible to control heat stressgenerated between the capacitor element 20 and the mounted semiconductorelement to be small.

Additionally, the base 21 may include aramid fiber and be made of theresin whose coefficient of linear expansion is within the range of 5–30ppm/K. In this case, since the base 21 is made of the resin whosecoefficient of linear expansion is within the range of 5–30 ppm/K, thecoefficient of linear expansion of the capacitor element 20 becomesclose to that of a semiconductor element having a silicon substrate.Thus, in a case where the semiconductor element is mounted on thesubstrate embedding the capacitor element 20 therein, it is possible tocontrol heat stress generated between the capacitor element 20 and themounted semiconductor element to be small.

Additionally, with the manufacturing method of a capacitor element 20according to the present invention, since the base 21 made of resin isused, formation of the vias becomes easier compared to a case where asilicon substrate is used. Thus, it becomes possible to reduce the timeinterval required for an operation to form the vias. In addition, sincethe base 21 is made of insulative resin, it becomes possible to directlyform a conductive layer on the top surface of the base 21 withoutforming an insulating film. Accordingly, compared to the case where asilicon substrate is used, manufacturing processes are reduced.

Additionally, with the semiconductor device substrate according to thepresent invention, since the capacitor element includes the base 21 madeof resin and thus the thickness of the capacitor element 20 is reduced,it also becomes possible to reduce the thickness of the semiconductordevice substrate. In addition, the top surface of the capacitor element20 serves as a semiconductor element mounting surface. Thus, the lengthof a conductive channel between the capacitor part and the semiconductorelement mounting surface is shortened to such an extent that the lengthcannot be made any shorter. Accordingly, it becomes possible to reduceparasitic inductance, which is inductance of the conductive channelbetween the capacitor part and terminals on the semiconductor elementmounting surface, to such an extent that the parasitic inductance cannotbe reduced any further. Hence, even if a semiconductor element ismounted that is operated at a high speed and is subject to parasiticinductance, power supply voltage is stabilized. Thus, it is possible torealize a semiconductor device substrate suitable for mounting asemiconductor element operated at a high speed.

Additionally, with the semiconductor device according to the presentinvention, since the semiconductor element is mounted on the exposed topsurface of the capacitor element 20, the length of a conductive channelbetween the mounted semiconductor element and the capacitor part isshortened to such an extent that the length cannot be made any shorter.Accordingly, it becomes possible to reduce parasitic inductance, whichis inductance of the conductive channel between the mountedsemiconductor element and the capacitor part, to such an extent that theparasitic inductance cannot be reduced any further. Hence, even if asemiconductor element is mounted that is operated at a high speed and issubject to the parasitic inductance, power supply voltage is stabilizedcompared to conventional techniques. In addition, it is possible tocontrol heat stress generated between the capacitor element 21 and thesemiconductor element to be small.

The present invention is not limited to the specifically disclosedembodiments, and variations and modifications may be made withoutdeparting from the scope of the present invention.

The present application is based on Japanese priority application No.2003-49716 filed on Feb. 26, 2003, the entire contents of which arehereby incorporated by reference.

1. A capacitor element configured to mount a semiconductor elementthereon, said capacitor element comprising: a base; and a capacitor partprovided on said base, wherein said base is made of a resin whosecoefficient of linear expansion is adjusted in accordance with acoefficient of linear expansion of the semiconductor element to fallwithin a range of 5 to 30 ppm/K.
 2. The capacitor element as claimed inclaim 1, wherein the capacitor part includes two opposing electrodes anda dielectric layer interposed therebetween.
 3. The capacitor element asclaimed in claim 1, wherein the base is made of an epoxy resin includinga filler for adjusting a coefficient of linear expansion of the epoxyresin.
 4. The capacitor element as claimed in claim 1, wherein the baseis made of a polyimide resin including a filler for adjusting acoefficient of linear expansion of the polyimide resin.
 5. The capacitorelement as claimed in claim 1, wherein the base is made of athermoplastic liquid crystal polymer.
 6. The capacitor element asclaimed in claim 1, wherein the base is made of a resin including aramidfiber for adjusting a coefficient of linear expansion of the resin.
 7. Acombination of a capacitor element and a semiconductor element wherein;said capacitor element is configured to mount a semiconductor elementthereon; said capacitor element comprises a base and a capacitor partprovided on said base; and said base is made of a resin whosecoefficient of linear expansion is adjusted in accordance with acoefficient of linear expansion of the semiconductor element that ismounted on the capacitor element.
 8. A semiconductor device substrate onwhich a semiconductor element having on a substrate may be mounted, saidsemiconductor device substrate comprising: a substrate body having abottom surface that serves as a mounting surface in which externalconnection terminals are arranged; and a capacitor element including: abase made of a resin whose coefficient of linear expansion is adjustedin accordance with the semiconductor element to be mounted to a valuebetween a coefficient of linear expansion of the substrate body and acoefficient of linear expansion of the substrate of the semiconductorelement; a capacitor part including two opposing electrodes and adielectric layer interposed therebetween; a plurality of terminals in atop surface of the capacitor element; and a plurality of terminals in abottom surface of the capacitor element, the capacitor element beingembedded in the substrate body, a top surface of the capacitor elementbeing exposed at a top surface of the substrate body and serving as asurface on which the semiconductor element may be mounted.
 9. Asemiconductor device, comprising: a semiconductor device substrate asclaimed in claim 8; and a semiconductor element, wherein thesemiconductor element is mounted on a top surface of the semiconductordevice substrate at which the capacitor element is exposed.
 10. Thesemiconductor device as claimed in claim 9, wherein the resin has acoefficient of linear expansion close to the coefficient of linearexpansion of the substrate of the semiconductor element.
 11. Thesemiconductor device as claimed in claim 10, wherein the substrate ofthe semiconductor element is made of silicon.
 12. The semiconductordevice as claimed in claim 9, wherein the resin has a coefficient oflinear expansion in a range of 5 to 30 ppm/K.
 13. The semiconductordevice substrate as claimed in claim 8, wherein the resin has acoefficient of linear expansion close to the coefficient of linearexpansion of the substrate of the semiconductor element.
 14. Thesemiconductor device substrate as claimed in claim 8, wherein the resinhas a coefficient of linear expansion in a range of 5 to 30 ppm/K.